Abstract
BACKGROUND: The biofouling marine tube worm, Hydroides elegans, is an indirect developing polychaete with significance as a model organism for questions in developmental biology and the evolution of host-microbe interactions. However, a complete description of the life cycle from fertilization through sexual maturity remains scattered in the literature, and lacks standardization. RESULTS AND DISCUSSION: Here, we present a unified staging scheme synthesizing the major morphological changes that occur during the entire life cycle of the animal. These data represent a complete record of the life cycle, and serve as a foundation for connecting molecular changes with morphology. CONCLUSIONS: The present synthesis and associated staging scheme are especially timely as this system gains traction within research communities. Characterizing the Hydroides life cycle is essential for investigating the molecular mechanisms that drive major developmental transitions, like metamorphosis, in response to bacteria.